I know of no one who claimed otherwise. However there are a group of people withing the US military who are from a specific group and who do kill their fellow soldiers.
.A couple of Americans' grave markers from Arlington
Yes, I do know that Sgt Singh is not a Muslim. My intent is to show that not all Americans who have died in recent conflicts fit into a specific group
United States v. Hasan K. Akbar - Wikipedia, the free encyclopedia
Nidal Malik Hasan - Wikipedia, the free encyclopedia
These guys aren't Sikhs either.